School of Mechanical Engineering Shem Tov Ido

School of Mechanical Engineering Seminar
Monday, November 12, 2018 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Heat transfer During Phase Separation of Partially Miscible Liquid-Liquid Systems in Mini-Channels

by

Idan Shem Tov

This research was carried out in the School of Mechanical Engineering under the supervision of Prof. Amos Ullmann

and Prof. Neima Brauner

The increasing power density of miniaturized equipment requires advanced cooling technologies to maintain allowable temperatures and ensure safe operation. An experimental study has been conducted to explore the possibility of enhancing the convective heat transfer in mini-channels by temperature-induced phase separation of partially miscible liquid-liquid mixtures. The convective heat transfer of three different mixtures: triethylamine-water, propylene glycol propyl ether-water and lutidine-water was tested under conditions of constant wall heat fluxes. The phase separation of the mixtures showed up to 120% cooling enhancement compared to single-phase flow, up to 25% enhancement compared to water and up to 150% enhancement compared to the standard coolant of ethylene glycol-water mixture. The best results were achieved with triethylamine-water mixture under low Re number and high heating power. The creation and migration of droplets when phase-separation takes place and the resulting local fluid mixing in the heated wall vicinity, was found to be the main mechanism leading to the HTC enhancement. The local mixing can be represented as higher effective fluid thermal conductivity (k). The effective k values, circulated via CFD simulations, are up to 2.1 larger than those of the corresponding single-phase flow values. In parallel to this research, USA group, in collaboration with our research group, showed that the effect of HTC enchantment is preserved upon downscaling to micro-channel.